As is well known in the art, fixed-wing aircraft typically require a runway to take off and land. And a runway requires a large surface area, be it man-made (e.g., asphalt, concrete, or a mixture of both) or natural (e.g., grass, dirt, gravel, ice, or salt). Unfortunately, because of land limitations or other space constrictions, not all situations facilitate runway usage. Therefore, rotorcraft and many smaller UASs are advantageous because they do not require a traditional runway. Moreover, runway independent UASs enable organic UAV deployment from locations where traditional runways may not be feasible, including, for example, ships, trucks, forward operating bases, clandestine locales, payload emplacements, and transitory emplacements.
Runway independence also offers greater flexibility and security than traditional aircraft. However, current runway independent UASs consist only of small-fixed wing platforms, which often weigh less than 135 lbs, and Vertical Take-Off and Landing (“VTOL”) platforms, such as helicopters, lift-fan aircraft, and so on. VTOL platforms, while effective, often lack endurance because they need large, inefficient power plants to take off and land. VTOL platforms generally include rotorcraft (e.g., a helicopter), although other kinds of systems using lift fans and jet engines are also practical. Despite the advances in VTOL technology, fixed-wing UASs typically offer greater performance than VTOLs, but they are not inherently runway independent. Therefore, specialized launch and recovery systems are needed to operate fixed-wing UASs without runways.
Historically, the launch system has been the lesser challenge for fixed-wing, runway-independent systems. Rail launchers, for example, have been used for ship-based floatplanes since before World War II, and they remain a low-risk method for modern UASs. Recovery, on the other hand, has traditionally been more difficult because of the challenges posed by, for example, precision engagement, energy absorption, and post-capture handling. Furthermore, fixed-wing recovery systems such as nets and vertical cables are typically only practical on small UAVs and UASs.
Known recovery approaches include nets, the Insitu SkyHook™, deep-stall/belly landing, nets, and low-speed parafoil recovery. Each of these legacy recovery approaches, however, has limitations for UASs having UAVs that weigh more than a few hundred pounds. These limitations may be attributed to, for example, unpredictable dynamic loads, poor precision, airframe-recovery system physical interface challenges, or excessive shock.
An example of a runway-independent technique for landing a smaller, fixed-wing UAV is to use a net to catch the UAS while in flight. For example, during the 1980s-1990s, battleships used the RQ-2 Pioneer, an early UAS employed in spotting for guns. In operation, the RQ-2 Pioneer could be launched from the fantail using a rocket-assist booster that would be discarded shortly after takeoff. Like modern UAVs, the Pioneer carried a video camera in a pod under the belly of the aircraft and transmitted live video to the ship's operators. To land the UAV, a net was deployed aft of the ship, and the aircraft was flown into the net. Though partially effective, using a net to catch a UAV in flight often resulted in damage to the airframe and a high loss rate. Similarly, positioning a net astern of the ship would increase the likelihood of loss if the aircraft missed the net and hit the ship instead.
The Insitu SkyHook™ allows runway-independent recovery of miniature robotic aircraft with a small operations footprint. The Insitu SkyHook™ uses a single cable hanging vertically from a boom to catch the aircraft on a wingtip hook. On land, the Insitu SkyHook™ may be used in wind conditions that would typically ground other aircraft. Though effective for miniature robotic aircraft, its method of hooking a wingtip and securing the air vehicle at a single point after capture, make the SkyHook™ ineffective for larger UAVs.
Accordingly, there is a need for systems and methods for improving recovery systems for fixed-wing, runway-independent systems. More specifically, there is a need for systems and methods for improving recovery systems for fixed-wing, runway independent systems for use with larger aircraft.